1. Field of the Invention
The present invention relates, in general, to variable capacity rotary compressors and, more particularly, to a variable capacity rotary compressor which allows an eccentric unit to be stably rotated.
2. Description of the Related Art
Generally, compressors have been used for a variety of refrigeration systems, such as air conditioners or refrigerators operated with a refrigerant sequentially and repeatedly flowing through a refrigeration cycle which includes compression-condensation-expansion-evaporation operations. In the general refrigeration system, the compressor compresses the refrigerant to highly pressurize the refrigerant prior to discharging the highly pressurized refrigerant to a condenser.
Recently, variable capacity compressors have been used in the general refrigeration systems, such as air conditioners or refrigerators, to vary the cooling capacity thereof as desired. Of the various variable capacity compressors, one includes variable capacity rotary compressors. In a variable capacity rotary compressor, a compression operation is executed in only one of first and second compression chambers having different capacities, thus varying compression capacity.
First and second eccentric units are installed in the first and second compression chambers respectively, of the conventional variable capacity rotary compressor. The eccentric units respectively cause first and second rollers, which are placed in the first and second compression chambers, respectively, to occupy eccentric posting from a rotating shaft to thereby execute a compression operation in the respective compression chamber while making a remaining one of the first and second rollers be released from eccentricity to thereby execute an idle operation, according to a rotating direction of the rotating shaft.
Each of the eccentric units includes first and second eccentric bushes and a locking pin. The first and second eccentric bushes are respectively fitted over first and second eccentric parts which are provided on an outer surface of the rotating shaft to be placed in the first and second compression chambers, respectively. The first and second rollers are fitted over the first and second eccentric bushes, respectively. The locking pin is mounted to a predetermined position of the eccentric unit, and causes one of the first and second eccentric bushes to occupy eccentric positions from the rotating shaft while causing a remaining one of the first and second eccentric bushes to be released from the eccentricity from the rotating shaft, when the, rotating shaft is rotated. Thus, the compression operation is executed in only one of the first and second compression chambers, each of which having different capacities, by an operation of the eccentric unit, according to the rotating direction of the rotating shaft, thus varying the compression capacity.